Soil and groundwater chemistry and vegetation distribution in a desert playa, Owens Lake, California

Abstract

Generation of fine particulate dust (PM10)from the Owens Lake play a creates a severe air pollution hazard in the western Great Basin of the United States. One proposed mitigation strategy involves establishment of native vegetation to stabilize and trap fugitive sand. This study investigated soil and groundwater chemistry and the distribution of native plant species in relation to salts and toxic ions in the soil and groundwater along four transects from vegetated dunes or shorelines to nonvegetated playa surfaces. Soluble salts in soil extracts along all four transects were dominated by Na+(mole fraction = 0.43–0.47), HCO3/CO3 2‐ (020–026), and Cl‐ (0.15–022). Distichlis spicata (L.) E. Greene and Atriplex parryi S. Watson were found at locations with very high salt concentrations (44–77 dS m‐1 saturated paste electrical conductivity EC). The ultimate limitation to plant distribution, however, appears to result from shallow anoxic groundwater restricting rooting depth. Groundwater chemistry was characterized by high pH (93–10), EC (3–54 dS m‐1), and sodium adsorption ratio (46–1223), and low redox potential (Eh = 7 to ‐240 mV). Shallow anoxic groundwater restricted the rooting zone of both D. spicata and A. parryi, and no vegetation was found when anoxic conditions were within 70 cm of the surface. An oxidized rooting zone greater than ∼1.5 m depth was present where cover of D. spicata and A. parryi was adequate for sand stabilization. Artificial dunes created with sand fences appear to be a substrate from which salts and borate‐B could be leached to levels tolerable by these species, and at the same time these raised microsites would provide a rooting zone of adequate depth for persistence of either naturally or artificially established native species.